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PESTS

1. Conopomorpha sinensisBradley, known as the lychee stem-end borer in China and thelychee fruit borer in Thailand, is the major pest in most seasons. This pest was previouslyrecorded asAcrocercops cramerella (now Conopomorpha cramerellaSnellen). C.sinensisand the related C. litchiellaBradley both attack lychee, the latter preferring leavesand shoots, while C. cramerella is restricted to rambutan and cocoa (Bradley, 1986).

C. sinensislays yellow, scale-like eggs 0.4 x 0.2 mm long on the fruit any time afterflowering, as well as on new leaves and shoots. Both lychee and longan are affected. Theeggs hatch in three to five days, with the larva immediately penetrating the fruit, leaf orshoot. They tunnel through the flesh of the fruit that often fall from the tree.

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2. Fruit-piercing moths such as Eudocima (Othreis) fullonia(Clerck), Eudocimasalaminia(Cramer) and Eudocima jordani(Holland) are important throughout Asia, Australiaand the South Pacific. The larvae of these moths develop on a variety of host plants suchas the coral tree, Erythrina, and vines of the Menispermaceae(Legnephora, Stephania, Fawcettia, Tinospora, Carronia, Sarcopetalum, Pleogyneand Hypserpa).

The moths have a proboscis that drills a neat hole in the skin of the fruit allowing them tosuck the juice from the flesh. Contamination of the wound with yeasts and bacteria carriedon the proboscis destroys the fruit. Drosophilaspp. attracted to the fermenting juice hastensdeterioration. Within a few days, a frothy exudate seeps from the fruit and stainsundamaged fruit close by.

3.Leaf Feeding Caterpillar

Oxyodes scrobiculataF. and Oxyodes tricolorGuen. occupy similar niches in Thailand andAustralia. In Australia, O. tricolorattacks trees in southern Queensland, but is not a pest inthe north. The castor oil looper,Achaea janata (L.), is a voracious feeder in Australia andoften infests trees in large numbers at the same time as O. tricolor. The caterpillars cancause severe defoliation.

In Thailand it is recommended that carbaryl be applied when there are two to three younglarvae per leaflet. Shaking the tree to dislodge larvae onto the ground improves theeffectiveness of the sprays. If 40 percent or more of larvae are parasitised, sprays should

not be necessary. In Australia, Bacillus thuringiensisBerliner (Bt), endosulfan or methomylmay be used when damaging populations of O. tricolorappear.

Oxyodes scrobiculataF

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Oxyodes tricolor

3. Leafrollers

Olethreutes perdulataMeyr. is an occasional pest in Queensland. Platypeplusaprobola(Meyrick) has also been recorded in Australia, China and India.AdoxophyescyrtosemaMeyr. and Homona coffeariaNietner attack trees in Guangzhou and Fujian. Thelatter species along with Homona difficilisis recorded in lychee, longan and rambutan in

Thailand. The orange fruit borer, Isotenes miserana(Walker), is another leafroller that alsoattacks flowers and fruit in Queensland.

P. aprobolais a minor pest in China and India where it attacks leaves and flowers. Howeverin Australia, it is part of a complex of species contributing to a significant loss of flowers. InChina,A. cyrtosemaand H. coffeariaalso feed on leaves, flowers and fruit.

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4. Beetle borers

The longicorn beetle,Aristobia testudo(Voet), is a serious pest of lychee and longan inGuangdong (Zhang, 1997). The beetle has one generation per year, with adults emergingfrom June to August. The females girdle branches by chewing off 10 mm strips of bark, withthe eggs laid on the wound and covered with exudate. The larvae hatch from late Augustand live under the bark until January when they bore into the xylem and create tunnels up60 cm long. In Taiwan Province of China, the white-spotted longicorn beetle,Anoplophora

maculata(Thomson), has a one-year life cycle. Adults emerge in spring and females insertabout twenty eggs individually into T-shaped incisions in the bark, 0.5 m above the soilsurface. The larval period lasts about ten months. In Australia, the longicornbeetle, Uracanthus cryptophagus, causes similar damage

5. Scarab beetles

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The elephant beetle,Xylotrupes gideon(Linnaeus), is important in all areas of Australia.The larvae develop in the soil or mulch where they feed on plant roots and humus. Thelarge, heavily-sclerotised and sexually-dimorphic adults emerge in spring. Later, they areattracted to the fruit as they ripen, especially those that have split or been damaged byparrots and fruit bats. They then start attacking sound fruit and can cause significanteconomic losses in the week or so leading up to harvest. Chemical control is unsatisfactory.Manual removal is effective in small trees, but difficult in large trees. Labour is relativelyexpensive in Australia, so this operation adds significantly to growing costs.

6. Soft scales

Pulvinaria (Chlorpulvinaria)psidii(Maskell), the green shield scale, infests trees in China,Taiwan Province of China, Australia and India. In Queensland, crawlers are produced inspring by adult scales that infest the leaves and twigs. Some of these crawlers move ontothe flowers and young fruit. The female scales are sometimes mistaken for mealybugs

because the egg masses that are covered in waxy filaments cover the ends of the scale.

Soft brown scale, Coccus hesperidumLinnaeus, is an occasional pest in Queensland,where chemicals have disrupted its parasitoids or it is protected by ants.Parasaissetianigra(Nietner) and Saissetia coffeae(Walker) infest trees in India along with C. psidii, butthey are not important.

These scales cause no damage as they feed, but the fruit become unmarketable whensignificant populations develop on the surface, as they often do in China, Taiwan Provinceof China and Australia. The scales also produce honeydew, which supports the growth ofsooty mould on infested fruit and panicles, and those below. These discoloured fruit are

downgraded or rejected in the market-place.

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8. Bugs

Several bugs belonging to Tessaritomidae attack lychee and longan throughout Asia andAustralia. Tessaritoma papillosaDrury occurs in southern China, Vietnam, Thailand,Myanmar, the Philippines and India, although Butani (1977) notes that Tessaritoma

javanicaThunberg and Tessaritoma quadrataDistant, are the main species in India. InAustralia, Lyramorpha roseaWestw. is known as the lychee stink bug, but rarely causesdamage.

In China, T. papillosahas one generation per year. Adults tend to aggregate and over-winter mostly on lychee and longan, but may also be found on other hosts in warmprotected areas. In spring, the females are attracted to trees with new flowers and shoots.They mate and lay up to 14 egg masses, each containing about 14 eggs, on the back ofleaves. Peak egg-laying occurs in March in Guangdong, but continues through toSeptember. The first nymphs mature in June, while there are still old adults in the trees.These old adults may have lived for up to a year, and generally die by August. The newadults do not mate immediately, but mature over winter and mate and lay eggs the following

spring.

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9. Mites

Erinose mite,Aceria litchii(Keiffer), also known as hairy mite, hairy spider, or dog ear mite,occurs throughout China, Taiwan Province of China, India, Pakistan and Australia. Femaleslay eggs singly on the leaf surface amongst the erineum induced by their feeding. The eggsare only 0.032 mm in diameter, spherical and translucent white. The mites are also small,only 0.13mm long and pinkish-white. All stages have only four legs, but are quite mobileand move easily from old leaves to infest new flushes. Their feeding stimulates theproduction of the erineum where they shelter and feed. Numbers vary with the cycle ofshoot growth, and are highest in summer and lowest in winter. Planting material obtained asmarcots may be infested if they have been taken from trees with the mites. Later

infestations occur when the mites are moved around the orchard by direct contact betweentrees, or carried around by orchard workers, wind and bees (Waite and McAlpine, 1992).

The mites attack new leaves causing a felt-like erineum to be produced on the under-surface. This forms as small blisters but may eventually covers the entire leaf, causing it tocurl. In severe cases, whole terminals may be deformed. The young erineum is silver-white,changing to light brown and dark reddish-brown, and eventually black. The greatestnumbers of mites are found in the intermediate stages.

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10. Gall flies

The leaf midge, Dasyneurasp., is a major pest in China (Zhang, 1997). LitchiomyiachinensisYang and Luo was described from specimens reared from galls on lychee leavescollected in Guangdong. The larvae over-winter in the galls produced as a result of theirfeeding. They pupate in the soil, with the adult flies initiating the first of eight overlappinggenerations from March. The midges prefer damp, closed canopies and dry out in exposed

areas. The adults lay eggs in lines on young leaves. The larvae then mine the leaf, causing'watery dots' that later become the galls. These turn brown and eventually drop out, givingthe leaf a shot-hole appearance.

In susceptible orchards, monitoring is not effective and preventive procedures are required.As with erinose mite, infested leaves can be removed after harvest and burnt. Later in thespring, methyl parathion (2.5 percent) at 75 kg per ha can be distributed under the trees, orisofenphos (0.001 percent) can be sprayed on the ground just prior to emergence of theadults. In autumn, isocarbophos (0.001 percent) should be sprayed twice over two weeksduring early leaf development (Zhang, 1997).

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11. Fruit flies

In Queensland, Bactrocera tryoni(Froggatt) occasionally attacks lychee, but is notconsidered economically significant. Females lay their eggs through the skin of the fruit,often utilizing cracks and wounds made by other pests. Although the eggs can hatch, thelarvae rarely survive (de Villiers, 1992), probably because of the juice in mature fruit drownsthem. The flies in Queensland, and related species in Africa and Hawaii, are capable ofovipositing through the skin of lychee, although some cultivars may be too thick. The onlyreal fly problem appears to be in South Africa, with Ceratatis rosa. However, the level ofdamage is still quite low. In South Africa, pheromone-baited traps can be used formonitoring populations. Control is achieved with bait sprays of protein hydrolysate mixedwith trichlorfon or mercaptothion. Alternatively, the panicles can be covered with paper bags

after the November fruit drop.

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DESEASES

1. Brown blight

Brown blight, Peronophythora litchii, is a major disease in both lychee and longan in Chinaand Thailand, although more important in the former. It is also reported to affect lychee inIndia. It is well described in Guangdong, and attacks leaves and panicles, as well as fruitthat can be infected right up to harvest. These infections all reduce production and shelf life.Flower panicles are particularly susceptible. Immature fruit turn brown, while those infectedbefore harvest have a white mildew growing on the skin.

The fungus over-winters in the soil or on old infected fruit, with the spores spread by wind,

rain and insects. Continuous wet weather and temperatures of 22 to 25C favour infection.It is suggested that growers clean up their orchard by removing shaded, infected and deadbranches after harvest. Copper oxychloride during winter and copper sulphate in spring alsohelp to reduce inoculum levels. These chemicals are replaced by fosetyl-Al or metalaxylduring flowering and fruit development.

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2. Anthracnose

Anthracnose, Colletotrichum gloeosporoides, is a major disease in Guangdong, and alsooccurs in India. Although it attacks leaves and branches, along with flowers and flowerstalks, infected fruit are unmarketable. Lesions on the leaves may appear as small roundlight grey areas, or irregular brown marks at the tips. In contrast, infections are much moreobvious on the flowers and fruit. Outbreaks are common after warm wet weather. The

fungus may not always cause immediate disease, which sometimes only becomes apparentafter harvest. Fungicides are used during an initial outbreak, but are not always effective.

A form of anthracnose caused byColletotrichum gloeosporioides (Glomerella cingulatainthe sexual state) also affects trees in Australia. Pepper spot causes superficial skinblemishes to the fruit, but does not effect production, fruit quality or shelf life. More than halfof the crop may be unmarketable in some orchards. The disease has been recorded on allcultivars, but is most severe on the popular Kwai May Pink.

The disease first appears as brown pinhead freckles, usually on the top of semi-mature fruit,in areas with overhanging branches. The spots do not increase in size, but rapidly turn

black. More spots appear on the top and sides of the fruit and may, by harvest, cover up tohalf of the fruit surface. Infections over-winter on the leaves, with the fungus potentiallyspread from nurseries to new orchards.

Until the appearance of pepper spot, lychee was generally free of diseases affecting fruit orfoliage in Australia. However, the occurrence of the disease has resulted in attempts tocontrol it using copper oxychloride and copper hydroxide. Calendar sprays of copper are

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costly and could lead to unacceptable residues if used close to harvest. Other chemicalssuch as mancozeb are being evaluated.

Tree decline

A slow decline and a sudden death have been recorded in China, Viet Nam and Australia,especially in poorly drained soils. It can affect the whole tree or just one or two branches.The symptoms include a sudden branch wilt that is followed by the decline of new growth onthe affected branch over a period. In other situations, the tips die without wilting. The tree orbranch may recover temporarily, but subsequently dies. Parts of the tree flush and grow,while other sections die.

A number of organisms including Phytophthora, Pythium and Fusariumhave been isolatedfrom the roots of trees, but it is not known where they cause the disease. A root rot causedby Clitocybeis reported to kill trees in the Philippines. Growers are advised not to plant onwaterlogged soils.

Armillariaoccasionally attacks roots and the base of trees of any age causing death or slowdecline. The fungus may survive in the soil, or on stumps and roots of various trees formany years. The planting sites need to be fumigated before establishing new trees in theorchard

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Parasitic algae and nematodes

A parasitic algae, Cephaleuros virescens, occasionally attacks trees in Australia causingloss of vigour. Cultivars such as Souey Tung and Haak Yip are very susceptible. It canbe controlled with two sprays of copper, before and after the wet season.

Nematodes such asXiphinema, Paratrichodorusand Helicotylenchus are a problem inSouth Africa, but whether they are significant in Australia and Asia is not yet clear. Post-

plant nematicides are used in South Africa, but have not been evaluated elsewhere.

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